Fix a missing parameter in Registrator for an 'unregistered' event
Add 'extraHeaders' parameter to UA.register() and UA.unregister() methods
Fix #52 in master.

Reporter: @FreeSWITCH
New stun_servers and turn_servers parameters
Fix #50. Allow password in URI userinfo
Fix #50 (totally). Allow password in URI userinfo

for user generated URIs
Enhance transport error handling

- Add disconnection 'cause' and 'code' properties to UA 'disconnection' event handler
- Emit UA 'disconnected' event every time UA is noticed about a transport disconnection regardles there are other servers to reconnect.
Fix. Allow case-insentivity in SIP grammar, when corresponds

Make header values, parameter names and parameter values case-insensitive
Enhance 'generic_param' grammar rule
Update LICENSE
Add 'Content-Length' header to every SIP response

..,whether or not it carries a body

- For interaction with implementations that require responses to have this header.
This is no longer version "0.2.1" but "devel".
Add URI and NameAddrHeader classes
Add JsSIP.URI and JsSIP.NameAddrHeader classes
Fix typo
Add 'stun_servers' and 'turn_servers' configuration parameters

Which allow setting multiple stun and turn servers
Cosmetic change.

- Uppercase 'C' (constants), 'Utils', and 'Exceptions' module names.
Fix #54. Allow configuration.uri username start with 'sip'
Fix access to a parsed 'To' header uri host
Allow non array value for 'stun_servers' and 'turn_servers'

...when specifying a single server.